Communication among computers is typically implemented over telephone lines. In analog or xe2x80x9cvoicexe2x80x9d communication, a modem provides the interface between the telephone line and a host computer to convert telephone line signals to computer signals and computer signals to telephone signals. Modern telephone communications are also implemented in digital format. In one digital configuration, analog or voice originated data is digitized and transmitted in digital format over the telephone line. A digital modem can receive the digitized data and covert it to computer readable data. Alternatively, digital data transmitted over telephone lines in ISDN format is received by an ISDN terminal adapter which provides the interface between the digital telephone line and the host computer.
In any of these configurations, an interface must be provided between the host computer and the telephone processing equipment, i.e., the modem or terminal adapter. The interface, in both hardware and software, provides for command and data communication between the user and the modem or terminal adapter. The interface also allows an application or driver running on the host computer to interface with the modem or terminal adapter. The interface, commonly referred to an xe2x80x9capplication programming interfacexe2x80x9d or xe2x80x9cAPI,xe2x80x9d transmits and receives commands and data to and from the modem or terminal adapter to implement computer/telephony communication.
Typically, the software application programming interface (API) runs on the host computer. It defines and maintains command and data structures required for communication between the host driver and the modem or terminal adapter. A conventional API is specific to the communication mode implemented on the applicable telephone line. That is, where ISDN communication is being provided, the API running on the host computer is specific to an ISDN terminal adapter. Where analog or voice is used, the API is specific to modem operation. Thus, traditionally, the host computer is interfaced to a single form of telephone line communication and runs an API applicable to only that single communication mode. If multiple communication modes are to be used, in a traditional configuration, the host computer must run an API for each mode.
The present invention is directed to an application programming interface. The API of the invention provides an interface between a host application, driver or user and telephone processing-equipment that is capable of processing ISDN telephone calls and analog or voice-originated calls. The API of the invention includes a host interface which transfers signals between the host computer driver or user and the telephone processing system. The API also includes a modem interface which transfers signals to and from the host interface and which transfers commands and data associated with analog or voice-originated telephone calls between the host interface and a modem processor within the telephone data processing system, the modem processor processing data associated with analog or voice-originated telephone calls. The API of the invention also includes an ISDN interface which transfers signals to and from the host interface and which transfers commands and data associated with ISDN telephone calls between the host interface and an ISDN processor in the telephone data processing system, the ISDN processor processing data associated with ISDN telephone calls.
The API of the invention can be used with a telephone processing system that is capable of processing data for both ISDN and analog-originated telephone calls. It can also process data for multiple simultaneous telephone calls of either type or of both types. Such a telephone data processing system is described in U.S. Pat. No. 5,949,762 which is entitled xe2x80x9cApparatus and Method For Processing Multiple Telephone Calls,xe2x80x9d issued from an application that was co-pending with the present application""s parent, and assigned to the same assignee as the present application. The contents of that patent are incorporated herein in their entirety by reference.
Despite the ability of the API of the invention to facilitate plural telephone call types, the specific type of call being processed is transparent to the user or driver. That is, the user can implement interface processing without knowing the type of call being processed. To this end, in the API of the invention, the host API is at the user level and accepts commands and data from the user. The API of the invention also includes two lower-level APIs, namely, a modem API and an ISDN API, which are implemented based upon the type of call being processed.
The modem API is implemented when voice or analog originated calls are processed. In this case, the host API processes and formats commands and data from the host or driver for modem processing. The modem API receives the modem commands and data from the host API and generates modem commands and data and forwards them to the modem processor in the telephone data processing system.
The ISDN API is implemented when ISDN calls are processed. For ISDN calls, the host API processes and formats commands and data entered by the host for ISDN processing. The command and data are received from the host API. In response, the ISDN API generates ISDN commands and data and forwards them to an ISDN processor in the telephone data processing system for ISDN processing.
The API of the invention provides numerous advantages over interfaces provided in conventional computer/telephone interface systems. The API of the invention provides the user with the flexibility of processing different types of telephone calls while not requiring the user to know which type of call is being processed. In other conventional systems, the API is specifically dedicated to a particular type of telephone call and, therefore, can only provide the user access to that type of call. The API of the invention provides the user with the ability to process different types of telephone calls, while maintaining transparency to the user, such that the user need not know the type of call being processed.
The API of the invention allows the user to process multiple telephone calls simultaneously, such calls being received in multiple channels of a basic rate ISDN (BRI) or a primary rate ISDN (PRI) telephone line. The ability to process multiple simultaneous telephone calls of multiple call types makes the API of the invention applicable to systems which regularly process multiple telephone calls simultaneously. Such systems could include Internet service providers. In conventional systems, both the hardware and the associated software interface had to be provided for each individual line. The system of the invention is therefore far less hardware and software intensive and, therefore, more efficient and less costly than conventional systems.